From 1977 to 1980, Mangel worked as a scientific analyst at the
Center for Naval Analyses (CNA), a federally funded research and development center supporting the
United States Navy. As a CNA employee, he served as the representative of the Operations Evaluation Group at
Naval Air Station Whidbey Island, working mainly on aspects of
electronic warfare and search problems. In 1980, Mangel joined the faculty at the
University of California, Davis, where he held positions in the Department of
Mathematics (1980–88) and the Department of
Zoology, which later became the Department of
Evolution and
Ecology (1988–1996). During his tenure, he co-founded the university's Graduate Programs in
Applied mathematics and in
Population biology. He served as Chair of the Department of Mathematics from 1984 to 1989 and as founding Director of the Center for Population Biology from 1989 to 1993. In 1996, Mangel moved to the
University of California, Santa Cruz (UCSC), where he held appointments in both
Environmental studies (1996–2002) and the Department of Applied mathematics and statistics (2002–2013). His administrative roles at UCSC included serving as Associate Vice Chancellor for Planning and Programs (1997–1999), Chair of the Department of Applied Mathematics and Statistics (2007–2009), and Chair of the Program in Technology and Information Management (2010–2012). Mangel was on the founding board of directors of FishWise, and chaired the board from 2013 to 2020. He retired in July 2013 and returned one month later with the title of Distinguished Research Professor, which he held until July 2025. In 2014, Mangel appeared as the Independent Expert for Australia in the case in the
International Court of Justice Whaling in the Antarctic: Australia v. Japan, in which the Court concluded that the Japanese Special Permit Whaling Program contravened the
International Convention for the Regulation of Whaling. Mangel has worked with colleagues in the Theoretical Ecology Group at the
University of Bergen (UiB) since 1994 and was appointed adjunct professor in 2010, moving to professor emeritus of Biology in 2021 on his retirement from UiB. == Research ==